JP2001162538A - Zinc alloy shot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide zinc alloy shots having good working efficiency and a long service life. SOLUTION: Zinc alloy shots consisting of 0.3 to 0.5 mass % of manganese as an additive and the rest zinc have an average grain size of 0.4 to 4.0 mm and hardness of 60 to 130 Hv. When necessary, 0.0001 to 0.05 mass % of aluminum may be combined with the zinc alloy shots.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc alloy shot used for removing burrs and surface treatment of die-cast products and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for removing burrs, scales, and the like of die cast products such as aluminum alloys, zinc alloys, and magnesium alloys, a shot blasting method (shot blasting) in which a large number of small spheres called shots are projected on a product to be processed. ) Is often used. Aluminum, steel, stainless steel, etc. have been widely used as the shot material used for this shot blasting shot.However, aluminum shots may cause an explosion due to dust generated during use. Stainless steel shots have a Vickers hardness of 20
There is a problem that the surface of the article to be treated is roughened because it is too hard, that is, 0 or more. In consideration of these problems, zinc shots using zinc as a shot material have recently been used. Zinc shot has the advantage that the risk of dust explosion is extremely low and blasting can be performed without damaging the surface of the workpiece.

[0003]

However, since the hardness of the zinc shot is as low as about 40 Hv, even if the same burr is removed, the blast time is long and there is a problem in work efficiency. Further, there is a problem that the life of the shot itself is short, and the surface of the article to be processed is blackened, which impairs the commercial value. Therefore, the present inventors have developed a zinc alloy shot having a hardness of 50 to 70 Hv in which zinc or the like is contained in zinc and applied for a patent earlier (Japanese Patent Application No. 10-13005).
4). However, conventionally, when the Vickers hardness is 70Hv or more, it has been said that the surface of the article to be processed is roughened and the surface roughness cannot be obtained. There is a need for zinc alloy shots having a degree of hardness.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a zinc alloy shot having a high work efficiency and a long shot life.

[0005]

According to the present invention, there is provided a zinc alloy shot comprising 0.3 to 5.0 mass% of manganese as an additive and zinc as a balance. Having an average particle size of 0.4 to 4.0.
mm and a hardness of 60 to 130 Hv. The zinc alloy shot of the present invention
0.0001-0.05% by mass of aluminum as required
May be included. According to these aspects, the hardness can be increased without significantly impairing the toughness of the material. Particularly when aluminum is added, it is possible to prevent the fluidity of the molten metal from deteriorating during the production.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail. First, the material constituting the zinc alloy shot according to the present invention will be described. (1) Zinc (Zn) is a main material constituting the shot. Zinc is not too hard, like steel or stainless steel, and is very unlikely to cause a dust explosion, like aluminum. (2) Manganese (Mn) is added as a component constituting the zinc alloy. The addition of manganese increases the hardness of the zinc alloy. (3) Aluminum (Al) is optionally added as a component of the zinc alloy similarly to manganese, but the addition of aluminum prevents a decrease in the fluidity of the molten metal. (4) Zinc, manganese and aluminum are
It is not necessary to use a material having a particularly high purity, but a material having a general purity is sufficient.

Next, the grain size of the zinc alloy shot according to the present invention will be described. This shot has an average particle size of 0.4 to
4.0 mm, preferably 0.6 to
It is about 1.8 mm. When the diameter is 0.4 mm or less, the mass per shot is small, so that the work efficiency such as deburring is reduced. In addition, it is heavy and may damage the article to be processed. The case where the average particle diameter is 0.6 to 1.8 mm is preferable from the viewpoint of surface treatment effects such as work efficiency and beautiful surface finish. In addition, it is preferable to use a shot that is once classified and classified for each predetermined particle size from the viewpoint of a uniform surface finishing treatment.

[0008] The hardness of the zinc alloy shot is preferably Vickers hardness of 60 to 130 Hv. When the hardness is 60 Hv or more, the life of the shot is extended. In addition, the working time for deburring can be reduced, and the working efficiency is increased. However, when the hardness is 130 Hv or more, the toughness of the zinc alloy shot becomes brittle, which is uneconomical. From the above, the hardness of the zinc alloy shot is 60 in Vickers hardness.
~ 130 Hv is preferred. Further, from the viewpoints of reliably shortening the blast time and extending the shot life, the hardness of the zinc alloy shot is preferably 70 to 100 Hv.

Next, the production of the zinc alloy shot according to the present invention will be described. A material such as zinc is mixed so as to have a predetermined blending ratio, and is preferably heated and melted in an inert gas atmosphere to obtain a molten metal. The molten metal flows down into water (in a cooling medium), and is spheroidized and solidified. Thereafter, it is dried and classified to obtain a zinc alloy shot having a predetermined grain size and hardness, which can be manufactured by a general shot manufacturing method. In this manufacturing method, when the temperature of the molten metal is low, the shot has an elongated shape, and the shot tends to be accompanied by a thread-like portion. On the other hand, when the temperature of the molten metal is high, the shot tends to be flat. Generally, the melt temperature is 450-650.
° C, preferably 500-600 ° C. When the water temperature (the temperature of the cooling medium) is high, the shape tends to be flattened, and the hardness tends to slightly decrease. In order to obtain a stable shot in quality, it is important that the temperature and water temperature of the molten metal are constant.

Next, the relationship between the composition and hardness of the zinc alloy will be described. (1) As shown in Table 1, when manganese is added to zinc, the hardness of the zinc alloy shot increases, but when the amount of manganese added is small, a predetermined hardness cannot be obtained. Therefore,
The processing time (blast time) is prolonged due to poor blast efficiency. Also, the shot life is shortened. On the other hand, if the amount of added manganese is too large, the hardness of the shot increases,
It is not preferable because the toughness is reduced and the material becomes brittle. On the other hand, if the amount of manganese added is large (5.0% by mass or more), the shape of the shot hardly becomes spherical at the time of manufacturing, and the yield is deteriorated. Similarly, when the amount of manganese added exceeds 5.0% by mass, the variation in hardness becomes large, which is preferable from the viewpoint of stable quality, and the fluidity of the molten metal also becomes poor. Therefore, the addition amount of manganese when aluminum is not added is preferably 3.0% by mass or less, and the hardness at this mixing ratio is about 100 Hv.

(2) Aluminum is added as necessary in order to prevent a decrease in the fluidity of the molten metal. If too much aluminum is added, as in the case of manganese, the shape of the zinc alloy shot is less likely to be spherical at the time of production, so that the yield is deteriorated, and the zinc alloy shot becomes unfavorable. Therefore, when aluminum is added, the addition amount is preferably in the range of 0.0001% by mass to 0.05% by mass, and more preferably in the range of 0.0001% by mass to 0.01% by mass.

[0012]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

Examples 1 to 5 and Comparative Examples 1 to 3 The zinc alloy shot of the example and the zinc alloy shot of the comparative example were produced as follows. First, manganese having the compounding amount shown in Table 1 was mixed with zinc, and this was heated and melted to obtain a molten metal.
Next, the molten metal is put into a graphite crucible having a nozzle of a predetermined diameter at the bottom, and a pressure of 29 to 49 KPa (0.3 to 0.5 kgf / cm ² ) is applied to the upper surface of the molten metal at a molten metal temperature of 500 to 600 ° C., and a nozzle tip is formed. Was dropped into water. As a result, the flow of the molten metal becomes spherical and solidifies.
Finally, this was collected, dried, classified and the like, and a shot having a particle size and hardness shown in Table 1 was obtained. The Vickers hardness is shown as an average value of 10 shots. Also, at the time of shot production, observe the fluidity of the molten metal,
A three-point evaluation of good (○), slightly good (△), and poor (x) was made. The results are also shown in Table 1.

[0014]

[Table 1]

From the above results, the desired hardness was not obtained in Comparative Example 1 in which the amount of manganese was lower than the range of the present invention, and the hardness was found to increase as the amount of manganese increased. However, the fluidity of the melt gradually deteriorated in the vicinity of Example 6 where the amount of manganese was 4.92% by mass. In Comparative Examples 2 and 3 in which the content of manganese was higher than that of the present invention, the fluidity of the molten metal was deteriorated. The obtained zinc alloy shot was very brittle.

Examples 6 to 23 and Comparative Examples 4 to 6 Tables 2 and 3 were prepared in the same manner as in Examples 1 to 5 and Comparative Examples 1 and 2 except that manganese and aluminum were added in the amounts shown in Table 2. A shot having the particle size and hardness shown was obtained. In addition, during the production of the shot, the fluidity of the molten metal was observed, and a three-point evaluation of good (○), slightly good (△), and bad (x) was performed. The results are also shown in Table 2.

[0017]

[Table 2]

From the above results, it can be seen that the shots obtained in Comparative Examples 4 and 6 in which the blending amount of aluminum is higher than the range of the present invention are less likely to be spherical.

[0019]

As described above, according to the zinc alloy shot according to the present invention, the hardness can be increased without greatly impairing the toughness of the material, and the life of the shot can be extended. . In addition, since blasting can be performed more efficiently than conventional zinc shots, processing time can be shortened and work efficiency can be improved.

Claims (2)

[Claims] 1. A zinc alloy shot comprising 0.3 to 5.0 mass% of manganese as an additive and the balance being zinc, having an average particle size of 0.4 to 4.0 mm and a hardness of 60 to 130 Hv. A zinc alloy shot. 2. The method according to claim 1, wherein the additive is aluminum.
The zinc alloy shot according to claim 1, comprising 0001 to 0.05% by mass.